Load-balanced NSAPI allocation for iWLAN

ABSTRACT

In one embodiment, a load balancer receives a message from a tunnel termination gateway (TTG) associated with a mobile device. The load balancer may receive messages from a plurality of TTGs. A gateway node in a plurality of gateway nodes in which to send the message is determined. The load balancer then assigns a NSAPI for use by the gateway node. For example, the NSAPI may be associated with a tunnel that is generated between the TTG and GGSN. The load balancer ensures that the assigned NSAPI is not currently in use at the gateway node. Thus, no overlapping of NSAPIs may occur even though the load balancer is processing messages from multiple TTGs for multiple gateway nodes.

RELATED APPLICATION

This Application is a continuation (and claims the benefit of priorityunder 35 U.S.C. §120) of U.S. application Ser. No. 11/767,419, filedJun. 22, 2007, entitled “LOAD-BALANCED NSAPI ALLOCATION FOR iWLAN,”Inventors Biswaranjan Panda, et al. The disclosure of the priorapplication is considered part of (and is incorporated by reference in)the disclosure of this application.

TECHNICAL FIELD

Particular embodiments generally relate to networking.

BACKGROUND

A packet data gateway (PDG) functionality may be performed using atunnel termination gateway (TTG) and a gateway GPRS support node (GGSN)as specified in 3GPP TS 23.234 appendix F. In this case, the TTG assignsa network service access point identifier (NSAPI), which is used toidentify a General Packet Radio Service (GPRS) tunneling protocol (GTP)tunnel between the TTG and GGSN. This is different from previousprocesses where the mobile device assigned the NSAPI. In the 3GPP TS23.234 appendix F architecture, a single TTG is associated with a singleGGSN.

The problem with using a one-to-one mapping between a TTG and GGSN isthat scalability is not provided. For example, when multiple GGSNs arebeing used, the load at one GGSN may be more than another GGSN, whichmay cause an overloaded GGSN to end a session even when another GGSN hasavailable resources. However, because of the one-to-one mapping, a TTGcannot send messages to the underutilized GGSN. Rather, the overloadedGGSN still must be used.

To increase scalability, load balancing may be used to spread use ofGGSN resources to underutilized GGSNs. However, because the TTG assignsthe NSAPI, it is possible that the same NSAPI may be sent to the sameGGSN by different TTGs. In this case, a tunnel may already be associatedwith the NSAPI. Then, a second TTG may assign the same NSAPI to a newtunnel for the same GGSN. In this case, the GGSN will tear down thefirst tunnel and initiate a new tunnel using the new NSAPI. This may endan active session prematurely.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an example of a system for providing NSAPI allocation.

FIG. 2 depicts a more detailed example of a load balancer.

FIG. 3 depicts an example of a method for assigning NSAPIs.

FIG. 4 depicts a more detailed example of a method for assigning NSAPIs.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

In one embodiment, a load balancer receives a message from a tunneltermination gateway (TTG) associated with a mobile device. The loadbalancer may receive messages from a plurality of TTGs. A gateway nodein a plurality of gateway nodes in which to send the message isdetermined. The load balancer then assigns a NSAPI for use by thegateway node. For example, the NSAPI may be associated with a tunnelthat is generated between the TTG and GGSN. The load balancer ensuresthat the assigned NSAPI is not currently in use at the gateway node.Thus, no overlapping of NSAPIs may occur even though the load balanceris processing messages from multiple TTGs for multiple gateway nodes.

In one embodiment, a method is disclosed. The method includes receivingat a load balancer a message from a TTG for a device, where the messageis to be used to create a tunnel, the load balancer determining a firstgateway node in a plurality of nodes to which to send the message, theload balancer accessing a plurality of mappings between a plurality ofNSAPIs and the plurality of nodes, the load balancer determining whethera particular NSAPI of the plurality of NSAPIs is currently in use at thefirst gateway node, the load balancer assigning the particular NSAPI foruse by the first gateway node, and the load balancer sending the messageto the first gateway node.

Example Embodiments

FIG. 1 depicts an example of a system for providing NSAPI allocation. Asshown, the system includes a load balancer 102, a plurality of TTGs 104,a plurality of GGSNs 106, a mobile device 108, and data services 110.

TTG 104 and GGSN 106 provide a packet gateway functionality 100 for thesystem. The packet data gateway function allows mobile device 108 toaccess data services 110 in a wireless local area network (WLAN), suchas a wireless fidelity (WiFi). In WLAN, a packet data gateway may beused. However, legacy carriers may use existing network devices, such asthe GGSN to implement the packet data gateway functionality. The packetdata gateway functionality is responsible for securing the trafficcoming over the WLAN, assigning IP addresses, authenticating users andservices, generating accounting information, and applying QoS policies.

Mobile device 108 may be any suitable mobile device. For example, mobiledevice 108 may include a cellular telephone, laptop computer, personaldigital assistant (PDA), personal e-mail device, etc. Mobile device 108may access TTG 104 through an access network 112. Access network 112 mayinclude a wireless local area network (WLAN), or other mobilecommunications system. Although a WLAN is described, it will beunderstood that any suitable wireless network may be used.

TTG 104 is a device that provides a tunnel between mobile device 108 anditself. In one embodiment, the tunnel may be an IPSec tunnel. TTG 104provides termination of the tunnel with mobile device 108.

GGSN 106 is configured to communicate with data services 110. GGSNallows service providers to provide data services to mobile device 108.GGSN 106 provides a gateway to data services 110. A gateway GPRS supportnode (GGSN) acts as an interface between the GPRS backbone network andthe external packet data networks (radio network and the IP network).

In one embodiment, a tunnel, such as a GTP tunnel, is created betweenTTG 104 and GGSN 106. Although a tunnel is described, it will beunderstood that any connection may be used between TTG 104 and GGSN 106.GGSN 106 identifies the GTP tunnel using an NSAPI that is assigned.Thus, communications from data services 110 may include the NSAPI andGGSN 114 uses the NSAPI to determine which tunnel the messages should besent through. Also, TTG 104 may use the NSAPI to send messages to GGSN106 through the correct tunnel.

Load balancer 102 may receive a packet data protocol (PDP) contextcreate message, which is a message to create a tunnel, from TTG 104.Load balancer 102 then dynamically assigns an NSAPI for the PDP contextcreate message. This message is then sent to GGSN 106, which can thencreate a tunnel between TTG 104 and GGSN 106. It should be noted thatany protocol may be used to create a tunnel and creating a tunnel isknown in the art.

As discussed in the background, the TTG conventionally assigned theNSAPI. If multiple TTGs assigned NSAPIs independently, it is possiblethey may assign the same NSAPI for identifying different tunnels to thesame GGSN. This results in the tearing down of an existing tunnel withthe same NSAPI. This is undesirable in that the two NSAPIs are probablyassociated with different mobile devices that have initiated differentsessions. Because the same NSAPI has been allocated for the tunnels,only one tunnel can be active.

However, particular embodiments allow load balancer 102 to determineNSAPIs for tunnels. Load balancer 102 is a central point for receivingtunnel create requests from TTGs 104 and can assign and keep track ofwhich NSAPIs were assigned to which GGSNs 106. Thus, load balancer 102can determine which GGSNs 106 have had which NSAPIs assigned. Then, whenan NSAPI is determined, load balancer 102 ensures that the NSAPIs do notoverlap for a specific GGSN 106.

FIG. 2 depicts a more detailed example of load balancer 102. As shown, amessage receiver 202, a GGSN determiner 204, an NSAPI reviewer 206,mappings 208, and an NSAPI assigner 210 are provided.

Message receiver 202 is configured to receive a message from TTG 104.For example, the message received may be an access request from mobiledevice 108. When the message is received, a tunnel may need to becreated between TTG 104 and GGSN 114.

The message from TTG 104 may or may not include an assigned NSAPI. Forexample, TTG 104 may be configured such that an NSAPI is not assignedwhen an access request is received because load balancer 102 assignsthem. However, to conform to prior specifications, TTG 104 may beallowed to assign an NSAPI but this NSAPI may be overwritten by loadbalancer 102 to ensure no overlapping at GGSNs 114.

GGSN determiner 204 determines a GGSN to send the access request to. Forexample, any load balancing techniques may be used to determine whichGGSN 106 should be assigned the access request. In one example, the GGSNthat has available resources is determined to service the accessrequest. Also, network bandwidth, cost, and other factors may be takeninto account in determining the GGSN.

NSAPI reviewer 206 is configured to determine NSAPIs that have alreadybeen assigned at the determined GGSN 106. For example, mappings 208 aremaintained for each GGSN and include an NSAPI to tunnel mapping. A tablelook-up may be performed to determine which NSAPIs have already beenassigned. Also, sequence numbers may be used where NSAPIs below acertain threshold have already been assigned. The NSAPI is then assigneda value that is not active at a specific GGSN 106. This allows NSAPIreviewer 206 to determine which NSAPIs have already been assigned for aspecific GGSN 106. The mappings may also identify which mobile device108 is associated with the NSAPI, which may allow for call continuity tobe provided as will be described later.

NSAPI assigner 210 then determines a unique NSAPI for the determinedGGSN 106. In one embodiment, NSAPI assigner 210 may generate a new NSAPIfor the access request. Also, if an NSAPI was assigned by TTG 104, theNSAPI may be overwritten. However, if the NSAPI assigned by TTG 104 isnot in use at the determined GGSN 106, then the NSAPI assigned by TTG104 may be used.

FIG. 3 depicts an example of a method for assigning NSAPIs. Step 302receives a message from TTG 104. The message may be for creating atunnel.

Step 304 determines a GGSN 106 in which to send the message. Forexample, load balancer 102 may determine an appropriate GGSN 106 tohandle the request.

Step 306 then dynamically assigns the NSAPI for the message. Forexample, an NSAPI that is unique to the determined GGSN 106 is assigned.

FIG. 4 depicts a more detailed example of a method for assigning NSAPIs.Because of the existence of multiple TTGs, load balancer 102 may processrequests from different TTGs that may go to the same GGSN 106.

Step 402 receives a first message from a first TTG 104. The firstmessage may be for a first mobile device 108-1.

Step 404 assigns an NSAPI for the message. This NSAPI is a value that isunique to a first GGSN 106-1.

Step 406 sends the message to GGSN 106-1. GGSN 106-1 may then establisha tunnel with TTG 104-1.

Step 408 receives a second message from a second TTG 104-2. This messagemay be for a second mobile device.

Step 410 assigns a second NSAPI than the NSAPI assigned in step 404.This is because the second message is going to be sent to the same GGSN106-1.

Step 412 then sends a message to GGSN 106-1 and GGSN 106-1 can thenestablish a second tunnel with TTG 104-2 using the second NSAPI.Accordingly, load balancer 102 assures that the NSAPIs assigned do notoverlap.

Particular embodiments may be used to provide call continuity. Forexample, a mobile device may start a call using a first access network.The call is connected through a first TTG 104-1 and GGSN 106-1. Duringthe call, mobile device 108 may attach to a different access network.For example, mobile device 108 may roam and attach to a WiFi network.The WiFi network may send an access request to a second TTG 104-2. Whena second message is received from a second TTG 104-2, load balancer 102may determine it is for mobile device 108. Load balancer 102 maydetermine the call is for the mobile device because an identifier, suchas an IP address, may be the same. Accordingly, it can determine that itshould be sent to the same GGSN 106-1. However, to avoid tearing downthe original tunnel, a different NSAPI may be assigned. Then, a tunnelmay be brought up between GGSN 106-1 and TTG 104-2. The call may behanded off and then the first tunnel is torn down. The call continuesusing the tunnel between TTG 104-2 and GGSN 106-1, however. Accordingly,call continuity may be provided using load balancer 102.

Particular embodiments provide many advantages. For example, loadbalancer 102 allows scalability in using multiple TTGs 104 and GGSNs106. Accordingly, GGSN resources may be optimally used. Also, loadbalancer 102 ensures that NSAPIs assigned to tunnels are unique and thusunnecessary tearing down of tunnels because of overlapping NSAPIs doesnot occur.

Although the description has been described with respect to particularembodiments thereof, these particular embodiments are merelyillustrative, and not restrictive. Although an NSAPI is described, itwill be understood that the NSAPI may be any identifier that couldoverlap at the GGSN. For example, the NSAPI may be other tunnelidentifiers.

Any suitable programming language can be used to implement the routinesof particular embodiments including C, C++, Java, assembly language,etc. Different programming techniques can be employed such as proceduralor object oriented. The routines can execute on a single processingdevice or multiple processors. Although the steps, operations, orcomputations may be presented in a specific order, this order may bechanged in different particular embodiments. In some particularembodiments, multiple steps shown as sequential in this specificationcan be performed at the same time. The sequence of operations describedherein can be interrupted, suspended, or otherwise controlled by anotherprocess, such as an operating system, kernel, etc. The routines canoperate in an operating system environment or as stand-alone routinesoccupying all, or a substantial part, of the system processing.Functions can be performed in hardware, software, or a combination ofboth. Unless otherwise stated, functions may also be performed manually,in whole or in part.

In the description herein, numerous specific details are provided, suchas examples of components and/or methods, to provide a thoroughunderstanding of particular embodiments. One skilled in the relevant artwill recognize, however, that a particular embodiment can be practicedwithout one or more of the specific details, or with other apparatus,systems, assemblies, methods, components, materials, parts, and/or thelike. In other instances, well-known structures, materials, oroperations are not specifically shown or described in detail to avoidobscuring aspects of particular embodiments.

A “computer-readable medium” for purposes of particular embodiments maybe any medium that can contain, store, communicate, propagate, ortransport the program for use by or in connection with the instructionexecution system, apparatus, system, or device. The computer readablemedium can be, by way of example only but not by limitation, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, system, device, propagation medium, orcomputer memory.

Particular embodiments can be implemented in the form of control logicin software or hardware or a combination of both. The control logic,when executed by one or more processors, may be operable to perform thatwhat is described in particular embodiments.

A “processor” or “process” includes any human, hardware and/or softwaresystem, mechanism or component that processes data, signals, or otherinformation. A processor can include a system with a general-purposecentral processing unit, multiple processing units, dedicated circuitryfor achieving functionality, or other systems. Processing need not belimited to a geographic location, or have temporal limitations. Forexample, a processor can perform its functions in “real time,”“offline,” in a “batch mode,” etc. Portions of processing can beperformed at different times and at different locations, by different(or the same) processing systems.

Reference throughout this specification to “one embodiment”, “anembodiment”, “a specific embodiment”, or “particular embodiment” meansthat a particular feature, structure, or characteristic described inconnection with the particular embodiment is included in at least oneembodiment and not necessarily in all particular embodiments. Thus,respective appearances of the phrases “in a particular embodiment”, “inan embodiment”, or “in a specific embodiment” in various placesthroughout this specification are not necessarily referring to the sameembodiment. Furthermore, the particular features, structures, orcharacteristics of any specific embodiment may be combined in anysuitable manner with one or more other particular embodiments. It is tobe understood that other variations and modifications of the particularembodiments described and illustrated herein are possible in light ofthe teachings herein and are to be considered as part of the spirit andscope.

Particular embodiments may be implemented by using a programmed generalpurpose digital computer, by using application specific integratedcircuits, programmable logic devices, field programmable gate arrays,optical, chemical, biological, quantum or nanoengineered systems,components and mechanisms may be used. In general, the functions ofparticular embodiments can be achieved by any means as is known in theart. Distributed, networked systems, components, and/or circuits can beused. Communication, or transfer, of data may be wired, wireless, or byany other means.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures can also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application. It isalso within the spirit and scope to implement a program or code that canbe stored in a machine-readable medium to permit a computer to performany of the methods described above.

Additionally, any signal arrows in the drawings/Figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted. Furthermore, the term “or” as used herein isgenerally intended to mean “and/or” unless otherwise indicated.Combinations of components or steps will also be considered as beingnoted, where terminology is foreseen as rendering the ability toseparate or combine is unclear.

As used in the description herein and throughout the claims that follow,“a”, “an”, and “the” includes plural references unless the contextclearly dictates otherwise. Also, as used in the description herein andthroughout the claims that follow, the meaning of “in” includes “in” and“on” unless the context clearly dictates otherwise.

The foregoing description of illustrated particular embodiments,including what is described in the Abstract, is not intended to beexhaustive or to limit the invention to the precise forms disclosedherein. While specific particular embodiments of, and examples for, theinvention are described herein for illustrative purposes only, variousequivalent modifications are possible within the spirit and scope, asthose skilled in the relevant art will recognize and appreciate. Asindicated, these modifications may be made to the present invention inlight of the foregoing description of illustrated particular embodimentsand are to be included within the spirit and scope.

Thus, while the present invention has been described herein withreference to particular embodiments thereof, a latitude of modification,various changes and substitutions are intended in the foregoingdisclosures, and it will be appreciated that in some instances somefeatures of particular embodiments will be employed without acorresponding use of other features without departing from the scope andspirit as set forth. Therefore, many modifications may be made to adapta particular situation or material to the essential scope and spirit. Itis intended that the invention not be limited to the particular termsused in following claims and/or to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include any and all particular embodiments andequivalents falling within the scope of the appended claims.

We claim:
 1. A method, comprising: receiving at a load balancer amessage from a tunnel termination gateway (TTG) for a device, whereinthe message is to be used to create a tunnel; the load balancerdetermining a first gateway node in a plurality of nodes to which tosend the message; the load balancer accessing a plurality of mappingsbetween a plurality of network service access point identifiers (NSAPIs)and the plurality of nodes; the load balancer determining whether aparticular NSAPI of the plurality of NSAPIs is currently in use at thefirst gateway node; the load balancer assigning the particular NSAPI foruse by the first gateway node; and the load balancer sending the messageto the first gateway node.
 2. The method of claim 1, wherein the messagecomprises a packet data protocol (PDP) context create message.
 3. Themethod of claim 2, wherein the assigning comprises dynamically assigningthe particular NSAPI for the PDP context create message.
 4. The methodof claim 1, wherein the message comprises an access request associatedwith a mobile device.
 5. The method of claim 1, wherein the assigningincludes overwriting an existing NSAPI provided in the message with theparticular NSAPI.
 6. The method of claim 1, wherein the determiningincludes employing a load-balancing technique that evaluates availableresources for servicing the message.
 7. The method of claim 1, whereinthe assigning includes assigning a value that is not active at the firstgateway node.
 8. The method of claim 1, wherein the accessing includesidentifying one or more mobile devices that are associated with one ormore NSAPIs.
 9. The method of claim 1, further comprising: determiningthat a particular call involves a mobile device; and sending aparticular message to a same network node that was previously associatedwith the mobile device.
 10. The method of claim 1, wherein the loadbalancer assigning the particular NSAPI for use by the first gatewaynode occurs when the load balancer determined that the particular NSAPIis not currently in use at the first gateway node.
 11. A load balancer,comprising: a processor; and a non-transitory computer readable media,wherein the load balancer is configured for: receiving, from a tunneltermination gateway (TTG), a message for a device, wherein the messageis to be used to create a tunnel; determining a first gateway node in aplurality of nodes to which to send the message; accessing a pluralityof mappings between a plurality of identifiers and the plurality ofnodes; determining whether a particular identifier of the plurality ofidentifiers is currently in use at the first gateway node; assigning theparticular identifier for use by the first gateway node; and sending themessage to the first gateway node.
 12. The load balancer of claim 11,wherein the message comprises a packet data protocol (PDP) contextcreate message.
 13. The load balancer of claim 12, wherein the assigningcomprises dynamically assigning the particular identifier for the PDPcontext create message.
 14. The load balancer of claim 11, wherein themessage comprises an access request associated with a mobile device. 15.The load balancer of claim 11, wherein the assigning includesoverwriting an existing identifier provided in the message with theparticular identifier.
 16. The load balancer of claim 11, wherein thedetermining includes employing a load-balancing technique that evaluatesavailable resources for servicing the message.
 17. The load balancer ofclaim 11, wherein the assigning includes assigning a value that is notactive at the first gateway node.
 18. The load balancer of claim 11,wherein the accessing includes identifying one or more mobile devicesthat are associated with one or more identifiers.
 19. The load balancerof claim 11, the load balancer being further configured for: determiningthat a particular call involves a mobile device; and sending aparticular message to a same network node that was previously associatedwith the mobile device.
 20. The load balancer of claim 11, wherein theload balancer further comprises: a message receiver element; adeterminer element; an identifier reviewer element; and an identifierassigner element.
 21. The load balancer of claim 11, wherein the loadbalancer is configured to assign the particular identifier for use bythe first gateway node if the load balancer determined that theparticular identifier is not currently in use at the first gateway node.22. The load balancer of claim 11, wherein the plurality of identifierscomprises a plurality of network service access point identifiers(NSAPIs).